Patent application PCT WO 99/50 854 proposes a zirconium-based alloy also containing, by weight, apart from unavoidable impurities, from 0.03 to 0.25% in total of iron, on the one hand, and of at least one of the elements of the group constituted by chromium and vanadium, on the other hand, having from 0.8 to 1.3% of niobium, less than 2000 ppm of tin, from 500 to 2000 ppm of oxygen, less than 100 ppm of carbon, from 5 to 35 ppm of sulphur and less than 50 ppm of silicon, the ratio of the iron content, on the one hand, to the chromium or vanadium content, on the other hand, being from 0.5 to 30.
The invention is based on observations made by the inventors in the course of a systematic study of the intermetallic phases and the crystallographic forms of those phases which appear when the relative contents of iron and niobium are varied while the contents of tin, sulphur and oxygen are described in the application mentioned above. It is also based on the observation, made experimentally, that the nature and the crystallographic form of the intermetallic phases containing zirconium, iron and niobium have a major influence on corrosion resistance in various environments.
In particular, it has been found that the presence of compounds Zr (Nb, Fe)2 having a crystalline structure with a hexagonal lattice, and of the phase βNb substantially improves corrosion in the aqueous medium which exists in the majority of pressurized-water reactors.